Monitoring of Heavy Metals in the complex "Nokoué lake - Cotonou and Porto-Novo lagoon" ecosystem during three years in the Republic of Benin

Abstract

Agricultural discharges and human activities affect complex "Nokoué lake, Cotonou and Porto-Novo lagoon ecosystems. This complex lagoon received effluent, sewage, municipal solid waste coming from neighboring cities. The present study aims to monitor heavy metals levels contamination in water, sediment and in aquatic species such as fish, oysters and shrimp during three years in twelve areas along the complex lake and lagoons. An atomic absorption spectrophotometer was used to measure heavy metals such as lead, cadmium, zinc and mercury. Analyses were done every year during three years. Water, sediment and aquatic species collected in the complex ecosystem are contaminated by zinc, cadmium, mercury, and lead with various levels varying according to years. It is important to take appropriate measures to limit the input of pollutants from human activities.